ok, i know you have gotten tons of responses but i hope you read mine. i tried to address alot of your concerns:)
your child having chunk on him signals he is not underweight. underweight would truly mean being very skinny. there is no problem if he is in the 15%, there is no problem if he is in the 50% and has always been. there is only a problem when a baby goes from like 85% to 20% at the next visit, or continually goes down and down(or up and up for that matter). being low on the scale is not an issue, its only a problem if you gain no weight at all over time.
he can have meat if you plan on eating meat. if you are not practicing a vegetarian/vegan lifestyle, he is old enough. he may not take to it right away, but as with all foods, keep trying. sometimes babies have to try something over and over again before accepting it. im not sure why she would not be more encouraging of him adding protein to his diet, regardless of weight issues. its adding another food group which is a good thing.
if he is very active, he will definately be leaner. my sisters baby was in the 90% for weight and then at 7 months was crawling. she has leaned out greatly over the last 2 months, and now my daughter(same exact age) who was always much less than her, is now much chunkier as she isnt active at all. when you start moving alot, you dont gain as much as you are using calories. also, you weight gain definately tapers off at a year old.
what horrible information your pediatrician gives as not encouraging nursing. breastmilk is filled with the fatty acids, and if his weight is of issue, or even if it isnt, breastmilk would be the best choice. why on earth would she suggest canola oil when you are breastfeeding. there is no need at all to add cows milk to a babys diet as long as you add yogurt and cheeses for calcium, you can google that for more information. the AAFP has a wonderful position paper i highly recommend. it goes over all the ways doctors and hospitals should do everything possible to encourage woman to breastfeed as it is proven to be the most beneficial, apparently she isnt doing that
http://www.aafp.org/online/en/home/policy/policies/b/brea....
it sounds once again that a doctor is using her personal opinion supremely over medical data and recommendations by the rest of the medical community. i highly suggest if you are concerned with his weight, or even if you just want to make sure he gets the most benefits, or if you just both enjoy and dont find it to be a problem, you should continue breastfeeding.
to add oil for the sole purpose of gaining weight is horrible advice imo. your son is just at his one year mark. eating fruits, vegetables, meats, protein along with eggs esp omega 3 ones which are an excellent source of good fatty acids is needed. im not saying oil IN your diet is bad, i would choose flaxseed or cod liver, but i still wouldnt ADD it. instead i would focus on eating foods that contain the fatty acids like nut butters, avocado, ects. again though, i wouldnt focus on that as being the factor with weight gain, which im still not sure you son even has an issue.
and if you are truly concerned about his fatty acid intake, YOU should be making sure you are eating enough fatty acids. do you like yogurt or cereal. i am super picky but put a little flaxseed in them, and they taste fine. add a little to a peanut butter sandwich. eat more fish and eggs, seeds, avocado. your intake goes to your breastmilk. there is no reason whatsoever he needs to have a bottle ever. if you decide to switch to a cup, it is your decision, but there is no medical reason you should not continue to just nurse instead(or even give breastmilk only in the cup). you are absolutely correct in breastmilk being able to sustain a baby. the food is complimenting it. my daughter has just started to eat a little banana, avocado, and carrots at 8 months old. we wont feed purees at all, but im sure she is more concerned with him not accepting solids, rather than it being a problem with his weight. 2 separate issues.
you sound very educated and on top of things. as long as your son doesnt have any medical issue, i think you are more than capable of researching on your own to decide what the best course of action is. doctors are never going to be able to be as up to date as a parent of a certain age group, for example- if you have a 6 month old, and are starting to feed them, you will research all the most up to date information about 6 month olds and food out there. a doctor of course is knowledgable, but considering the age frame and content matter they deal with, they cannot be an expert of every age at every moment with the most up to date info. good luck, dont worry.